1. Field of the Invention
This invention relates to a fixing device and an image forming apparatus.
2. Description of Related Art
Electrophotographic printers conventionally transfer toner corresponding to printing images onto a paper and fix the toner to the paper with application of heat and pressure. A prior art fixing device used in such an electrophotographic printer is arranged with plural heaters and plural temperature detecting means, which are disposed at different places in a longitudinal direction of a fixing member. The plural heaters are independently controlled based on temperature detection results given from the respective temperature detecting means, thereby rendering stable the temperature profile in the longitudinal direction of the fixing member. To reduce the maximum power consumption by selectively and exclusively driving the plural heaters, the plural heaters are controlled to be alternatively driven based on the temperature detection results given from the respective temperature detecting means to render stable the temperature profile in the longitudinal direction of the fixing member.
Japanese Unexamined Patent Publication No. H08-286552 discloses a fixing device formed with two temperature detection sensors arranged on a surface of a heating roll corresponding to regions at which the heat generating amount in an axis direction of the lamps is relatively large and formed with a power control circuit variably controlling the power supply amount fed to the two lamps based on temperature detection results obtained from the two temperature detection sensors.
With the prior art device, however, there raises a problem that fixing control becomes complicated because of frequent switching operation of the heating means. It is therefore an object of the invention to provide a fixing device for making fixing operation simple in consideration of the above technical problem.